I was brainstorming, but if Wright wants to use Lang, what if they did something where at the beginning of the Avengers 2, Pym is already Ant-Man but is retired and his superhero career was relatively recent, only 10-15 years ago. That way his story arc in A2 could be him coming out of retirement to help with Thanos or whoever the villain ends up being.

As for Janet, they can include her origin story as a subplot within the film or she has also retired.

That way, we still get to see the Pyms play a role in the Avengers 2, while Wright can still adapt 'To Steal an Ant-Man' in his film six months later.